Tire valve core

ABSTRACT

Tire valve core has drawn metal shell with ridges on either side of plastic shell gasket and grooves aligned with edges of gasket to receive plastic flow and anchor gasket securely.

United States Patent 1191 McAnally 1 1 Jan. 23, 1973 I TIRE VALVE CORE{56] References Cited [75] Inventor: zlilton Beasley McAnally,Nashville, UNITED STATES PATENTS enn.

. 3,000,390 9/1961 Hosking ..l37/234.5

[73] Assgnw i Maguiacwr'ng 3,433,389 3/1969 Puster ..|37 234.5 x

3,561,467 2/1971 Lutz ..137 234.5

[22] Filed: Aug. 5, 1971 [21 1 App No 169 235 Primary Examiner-Harold W.Weakley Anomey-Dallett Hoopes [52] U.S. Cl ..l37/234.5, l37/543.l9, [57]ABSTRACT [51] Int. Cl ..Fl6k 15/20 r valve re h drawn metal shell withridges on [58] Field Of Search ..l37/234.5, 543.l9; 251/368 either sideof plastic shell gasket and grooves aligned with edges of gasket toreceive plastic flow and anchor gasket securely.

6 Claims, 3 Drawing Figures PATENTEDJAHZSIQH 3,712,328

Milfon B Ana 94m a ATTORNEY TIRE VALVE CORE This invention relates to atire valve core. More specifically, the invention relates to a corehaving a drawn sheet metal shell surrounded by resilient plastic sealingmeans.

The prior art contains a number of disclosures of cores which areadapted to be screwed into tire valve stems. These cores invariably havea metal body surrounded by a rubber or plastic sealing element andcontain valve means in the form of a pin disposed axially of the coreoperable from the top thereof to unseat a plug at the bottom of thebody.

Especially effective sealing means surrounding the shell is disclosed inthe US. Pat. No. 2,932,531 to Briechle. In that patent, the sealingmeans comprised a polytetrafluoroethylene (PTFE) gasket surrounding thebody and fitting into a groove therearound. PTFE and closely relatedplastics have the advantage in such usage that they will not stick butinstead easily come away from their engagement against the shoulder ofthe stern when the core is removed.

In the Briechle core, the need for positive anchoring of the slipperyPTFE gasket is recognized by the provision on the plug'of sharpindentations forming radial shoulders adapted to hold the ends of thegasket. This structure has been regarded as essential to counteract thetendency of the slippery PTFE to, in removal of the core, simply slideoff the end of the body.

The need for sharp corners and radial shoulders on a core body to holdthe PTFE gasket has led to the impression in the past that core bodiesfor use with PTFE or other self-lubricating plastics had to be machinedfrom solid stock. Thus, even though tubular structures could beinexpensively drawn from sheet material, the inability to provideshoulders on such drawn shapes has, in the past, led manufacturers tothink that machining operations on solid stock were necessary.

Under the present invention, a simple but ingenious configuration of adrawn body makes its use compatible with the use of a PTFE or similarplastic gasket material. There is thus provided a less expensive corefeaturing an effective seal with the valve stem and at the same timeassuring an integrity of assembly comparable to that of earlier machinedcore bodies surrounded by PTFE seals.

Other objects of the invention will be apparent from the followingspecification including the drawings wherein there is disclosed apreferred but non-limiting example of structure embodying the invention.

In the drawings:

FIG. 1 is a sectional view of a core embodying the invention;

FIG. 2 is a plan elevation, having the gasket partly stripped away, of adrawn body part; and

FIG. 3 is a greatly enlarged sectional view showing the assembly of thegasket and the plug engaging the shoulder of the valve stem.

Referring more specifically to the drawings, a core embodying theinvention is generally designated in FIG. 1. It comprises a core body 12including a machined head 14 and a drawn sheet metal shell 16. The lowerend of the shell presses a seat 18. A valve pin is supported at itsupper end in a conventional bridge 22 and centered at its lower end by aconical centering flange 24. A sealing washer 26 is supported in a valvehead 28 mounted on the bottom end of the pin 20.

A helical closing spring 30 surrounds the pin 20 and is disposed betweenan upwardly facing shoulder 32 formed in the shell and a stop shoulder34 on the pin as is conventional.

As shown in FIG. I, the lower end of the head 14 presents a bottomopening which is surrounded by an inward lip 36. The upper end of theshell 16 is formed with a flared mouth 38 and in assembly, as isconventional, the bottom opening is closed so that the lips 36 enclosethe flared mouth 38 and hold the shell and head together.

Attention is now directed to the shape of the shell intermediate itsends. As shown, the shell is formed with a pair of spaced peripheralridges 40 and 42. Intermediate the ridges, a pair of peripheral grooves44 and 46 are formed in the shell. As shown, the grooves are disposedrespectively adjacent the beads 40 and 42 on the side of the respectivebead which is more proximate the other bead. There is thus formed in theshell a substantial wall or shoulder intermediate each rib and groove,as at 48 and 50 (FIG. 3). The area of the shell intermediate the groovesmay be barrel shaped, but preferably is frusto-conical in shape.

As shown, a PTFE gasket or seal 52 comprising a continuouscircumferential band is disposed about the shell between the ridges 40and 42. Preferably, the lower portion of the gasket presents asawtoothed profile as at 54 in accordance with aforementioned Briechlepatent.

In assembly, the PTFE gasket 52, which may be a short section from anextruded tube and sized smaller than the area of the shell it is tosurround, is slipped up over the end of the shell so that its marginsalign with grooves 44 and 46. The gasket, retaining its memory, will inthese areas, flow, shrink into, and closely hug into the inward grooves44 and 46 respectively. Under compression against the sidewall of thetire valve stem S additional plastic will flow into the grooves. Thisinward disposition of the plastic effectively anchors the gasket on theshell and makes these two pieces virtually unitary.

Experience has shown that some sort of grooves 44 and 46 or depressionsadjacent the ridges 40 and 42 are necessary and essential to theinvention to provide an anchor for the gasket. It is similarly necessarythat the diameter of the shell at some point intermediate the grooves besubstantially larger than the diameter at the grooves.

It will be seen that there is presented a new valve core especiallyuseful as a tire valve, but not necessarily limited thereto, having adrawn shell which effectively holds gaskets of PTFE and the like andwhich by virtue of having been drawn is much less expensive to producethan earlier machined versions. The shell is useful in a short" core,but may also be used in a long core. The success of the new shell isattributable to the configuration described although variations from thespecific embodiment shown will be possible under the invention withinthe following claim language:

I claim:

1. In a tire valve core comprising a two-piece core body including amachined head and a shell, the machined head being exteriorly threadedand having a bottom opening with an inward lip thereabout, the upper endof the shell having an outward flare, the lip at the lower end of thehead being crimped inward to enclose the flare and hold the shell, agasket of selflubricating plastic snugly surrounding the shell, andvalve means disposed in the body; the improvement wherein the shell isof drawn sheet metal and is formed with a pair of spaced peripheralbeads and a pair of spaced peripheral inward grooves disposedrespectively adjacent the beads on the side of the respective bead whichis more proximate the other bead and wherein the plastic gasket is acontinuous band with the margins of the band flowing into and closelyhugging into the inward grooves respectively.

2. A tire valve core as described in claim 1 wherein the plastic of thegasket is a fluoride-containing polymer.

3. A tire valve core as described in claim 2 wherein the plastic of thegasket is polytetrafluoroethylene.

4. A tire valve core as described in claim 1 wherein the exteriorsurface of the gasket is of saw-toothed 5. A tire valve core asdescribed in claim 1 wherein the shell, between the lowermost depths ofthe two grooves presents a smooth frusto-conical shape.

6. In a valve core comprising a two-piece core body including a machinedhead and a shell, the machined head being exteriorly threaded and havinga bottom opening with an inward lip thereabout, the upper end of theshell having an outward flare, the lip at the lower end of the headbeing crimped inward to enclose the flare and hold the shell, a gasketof self-lubricating plastic snugly surrounding the shell, and valvemeans disposed in the body; the improvement wherein the shell is ofdrawn sheet metal and is formed with at least one peripheral bead and aperipheral inward groove disposed adjacent the bead and wherein theplastic gasket is a continuous band with a margin of the band buttingagainst the bead and flowing into and closely hugging into the inwardgroove.

1. In a tire valve core comprising a two-piece core body including amachined head and a shell, the machined head being exteriorly threadedand having a bottom opening with an inward lip thereabout, the upper endof the shell having an outward flare, the lip at the lower end of thehead being crimped inward to enclose the flare and hold the shell, agasket of selflubricating plastic snugly surrounding the shell, andvalve means disposed in the body; the improvement wherein the shell isof drawn sheet metal and is formed with a pair of spaced peripheralbeads and a pair of spaced peripheral inward grooves disposedrespectively adjacent the beads on the side of the respective bead whichis more proximate the other bead and wherein the plastic gasket is acontinuous band with the margins of the band flowing into and closelyhugging into the inward grooves respectively.
 2. A tire valve core asdescribed in claim 1 wherein the plastic of the gasket is afluoride-containing polymer.
 3. A tire valve core as dEscribed in claim2 wherein the plastic of the gasket is polytetrafluoroethylene.
 4. Atire valve core as described in claim 1 wherein the exterior surface ofthe gasket is of saw-toothed profile.
 5. A tire valve core as describedin claim 1 wherein the shell, between the lowermost depths of the twogrooves presents a smooth frusto-conical shape.
 6. In a valve corecomprising a two-piece core body including a machined head and a shell,the machined head being exteriorly threaded and having a bottom openingwith an inward lip thereabout, the upper end of the shell having anoutward flare, the lip at the lower end of the head being crimped inwardto enclose the flare and hold the shell, a gasket of self-lubricatingplastic snugly surrounding the shell, and valve means disposed in thebody; the improvement wherein the shell is of drawn sheet metal and isformed with at least one peripheral bead and a peripheral inward groovedisposed adjacent the bead and wherein the plastic gasket is acontinuous band with a margin of the band butting against the bead andflowing into and closely hugging into the inward groove.